A CV joint is a structure that permits two shafts to connect to each other. In particular a CV joint can be used when transferring rotational energy from a first shaft to a second shaft, when a non-zero angle exists between the two shafts, or when the shafts are expected to move relative to each other during use. A typical application for a CV joint is in a passenger vehicle, however, they are also used in numerous other applications.
A CV joint typically includes a bearing, comprising an inner race, an outer race, a plurality of rolling elements positioned between the inner and outer races, and a cage which retains the balls. The first shaft is mounted to the inner race, and typically extends through an aperture in the inner race. The second shaft is mounted to the outer race. On one side of the bearing, a flexible boot typically mounts between the first shaft and a member called a front can, which itself is connected to the outer race. The flexible boot, typically referred to as a CV joint boot, protects the other side of the bearing from contamination by debris or dirt from the surrounding environment during use. On the other side of the bearing there is some structure that protects the bearing from contamination by debris or dirt from the surrounding environment during use.
Lubricant is typically used in the bearing to inhibit wear of the rolling elements. During use of the CV joint, however, some lubricant can migrate out from the bearing and eventually can make its way into the interior of the CV joint boot. Depending on a variety of factors, the presence of enough lubricant in the boot can overstress the boot at a sufficiently high rotational speed of the joint, eg greater than 5000 rpm, and can ultimately lead to tearing of the boot during use.
Consequently, there is a need for a way of inhibiting the migration of bearing lubricant into the interior of the CV joint boot during use of the CV joint.